Under the High Rate Packet Data (HRPD) standard defined by the 3rd Generation Partner Project 2 (3GPP2), when an Access Terminal (AT) moves from one subnet into another subnet in a dormant state, the AT is required to initiate a Unicast Access Terminal Identifier (UATI) request—updating the UATI of the AT and routing-related information of its corresponding user. To reduce UATI requests resulting from frequent moves between subnets of the AT in a dormant state, the HRPD 3.0 protocol in 3GPP2 provides a function of SecondaryColorCode. When a dormant AT moves from a source subnet to a target subnet, if ColorCode stored by the AT matches the SecondaryColorCode of the target subnet, then the AT does not initiate a UATI request. The AT in the target subnet is in an idle state.
Therefore, as a dormant AT moves into a target subnet, if the AT does not establish a connection with the target subnet after comparing the stored ColorCode in the AT with SecondaryColorCode of the target subnet, then neither the source subnet nor the target subnet may directly know the AT's location.
Under the current HRPD standard, if a dormant AT does not establish connection with a target subnet, the AT may be connected with the target subnet through communications between subnets, and a source subnet may call the AT by paging across subnets.
FIG. 1 illustrates a diagram of signaling between HRPD subnets. AT (100) establishes a session in a source subnet (102), and saves the session information. In a SectorParameters message of Source Subnet (102), ColorCode is 7. Target Subnet (104) has a SecondaryColorCode of 7. Therefore, when AT (100) moves to Target Subnet (104) in a dormant state, AT (100) does not initiate a UATI request, because the ColorCode stored by AT (100) matches the SecondaryColorCode of Target Subnet (104).
When Source Subnet (102) needs to page AT (100), paging will first be done within Source Subnet (102). If paging within Source Subnet (102) fails, Source Subnet (102) will find AT (100) in Target Subnet (104) through communications between Source Subnet (102) and Target Subnet (104).
Since Target Subnet (104) does not have session information of AT (100), if AT (100) needs to establish a connection with Target Subnet (104), Target Subnet (104) may obtain session information of AT (100) in Source Subnet (102) through subnet communications, and establish the connection.
Thus, by utilizing the SecondaryColorCode feature, an AT moving around in a dormant state from one subnet to another subnet may not update UATI, and signaling between an Access Network (AN) and the AT may be transmitted through subnet communications.
When a call from a source subnet needs to be connected to an AT, since the AT has moved to a target subnet, paging the AT within the source subnet will not succeed. Then, paging may be made between the source subnet and the target subnet to get to the AT. An unsuccessful paging within the source subnet, and paging across the subnets obviously bring forth greater paging delay, or even missing pages, resulting in poor call connection performance.
When the AT in the target subnet initiates a call request, the target subnet will have to retrieve session information associated with the AT from the source subnet, since the target subnet does not have such information. After the session information is transferred to the target subnet, the call set-up may proceed, and A8, A10 and UATI information is updated. This delays call set-up for the AT, and results in poor call connection performance.
Therefore, there is the need for an effective method of signaling when an AT moves around within two or more subnets, particularly while in a dormant state.